A secondary enclosure, typically consisting of a wall or berm, which surrounds a tank or fluid-handling mechanism, intended to contain any spills or leaks.

The most important of these [secondary containment] provisions are bunds, which are enclosures capable of holding liquids that may escape from the vessels and pipes within the bund wall. — Second progress report on the Buncefield investigation [1]

(India) A perennial ("wet") or seasonal ("dry") pond constructed in a depression and in which fish are stored, typically for breeding.